Microstructure and mechanical properties of Mg–Zn–Dy–Zr alloy with long-period stacking ordered phases by heat treatments and ECAP process

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 611; pp. 108 - 113
• Main Authors: Zhang, Jinshan, Xin, Chao, Nie, Kaibo, Cheng, Weili, Wang, Hongxia, Xu, Chunxiang
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 12.08.2014; Elsevier
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; ECAP; Elasticity. Plasticity; Elongation; Equal channel angular pressing; Exact sciences and technology; Grain boundaries; Heat treatment; LPSO phase; Materials science; Mechanical properties; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Mg–Zn–Dy–Zr alloy; Microstructure; Other heat and thermomechanical treatments; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phases; Physics; Precipitation; Stacking; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Treatment of materials and its effects on microstructure and properties; Ultimate tensile strength; Mechanical properties; Mg–Zn–Dy–Zr alloy; Heat treatment; Microstructure; ECAP; LPSO phase; Grain boundaries; Network structure; Crystal defects; Ultimate strength method; Stacking sequence; Ductility; Precipitates; Heat treatments; Tensile strength; Casting; Precipitation; Eutectics; Property structure relationship; Tensile properties; Mg-Zn-Dy-Zr alloy; Elongation (mechanics); Crystal structure
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2014.05.067

A high-strength and good-ductility Mg93.83Zn1.5Dy4.5Zr0.17 (at%) alloy containing long-period stacking ordered (LPSO) phases was prepared by conventional casting, heat treatments and an equal channel angular pressing (ECAP) process. The microstructure evolution, especially the second phases (LPSO phases), and the mechanical properties of Mg93.83Zn1.5Dy4.5Zr0.17 alloy tailored by different treatments were investigated. The results showed that the microstructure of the as-cast alloy was composed of α-Mg matrix, block LPSO phases and eutectic phases. And, the latter two phases formed a continuous network structure in the vicinity of grain boundaries. After heat treatments, the eutectic phases in the vicinity of the grain boundaries all dissolved, while large amounts of block LPSO phases and lamellar phases were precipitated. The LPSO phases were refined obviously and a large number of kinks emerged after the ECAP treatment. The as-cast alloy exhibited ultimate tensile strength and elongation of 152MPa and 3.58% at room temperature, respectively. After a series of treatments, the ultimate tensile strength of the alloy was increased to 322MPa with elongation of 23.6%.